For example, in silicon-dioxide-film adhesion processing according to a moisture oxidation method used by semiconductor manufacturing facilities, a high-purity water supply is required, and, in usual cases, the necessary high-purity moisture is supplied by a moisture generating reactor as shown in, for example, FIG. 8.
More specifically, this moisture generating reactor is structured so that, as disclosed by International Publication No. WO97/28085 and by Japanese Patent No. 3639469, a reactor body 1 having a space 4 thereinside is formed by assembling an inlet-side reactor body member 2 and an outlet-side reactor body member 3 together so as to face each other, and the reactor body 1 is provided with a source gas inlet 5, a moisture gas outlet 6, a reflector 7, and a reflector 8, and, furthermore, a platinum coating film 9 is formed on an inner surface of the outlet-side reactor body member 3.
When moisture is generated, mixed gas G consisting of oxygen O2 and hydrogen H2 is first supplied from the source gas inlet 5 into the space 4, and is then stirred by the reflectors 7 and 8 while oxygen O2 and hydrogen H2 are activated by the catalytic action of the platinum coating film 9. Thereafter, activated oxygen O2 and hydrogen H2 are allowed to instantaneously react with each other in a non-combustion state below a temperature of 450° C., thus generating water. The resulting water is discharged from the moisture gas outlet 6 out of the reactor body 1 in the form of moisture gas W.
In spite of the fact that the moisture generating reactor structure, as shown in FIG. 8, is very small (for example, about 114 mm in outer diameter and about 35 mm in thickness), the moisture generating reactor can continuously generate moisture gas W of about 2 SLM (which is a moisture gas quantity calculated in a standard state at a temperature of 0° C. and at 1 atmosphere of pressure, wherein SLM is an abbreviation for “Standard Liters per Minute”) by the catalytic reaction performed below a temperature of 400° C. Thus, the moisture generating reactor structure shown in FIG. 8 has an excellent, practicable effect.
However, in the moisture generating reactor shown in FIG. 8, if the supply of the source gas G is increased in amount so as to increase the amount of moisture generation, a rise in temperature of the outlet-side reactor body member 3 becomes steep, and the temperature of the internal space of the reactor body 1 will rise and approach the explosive temperature of the source gas G, which is H2—O2 mixed gas, and, as a result, an extremely dangerous state will be reached. Additionally, if the supply of the source gas G is increased in amount, the rate of reaction between hydrogen H2 and oxygen O2 will fall, and oxygen O2 and hydrogen H2 will enter into, and mix with, moisture gas W without allowing oxygen O2 and/or hydrogen H2 to react with each other, and, as a result, various disadvantages will occur on the process side where the moisture gas W is used. Additionally, if the temperature of the reactor body 1 rises, the platinum coating film 9 formed on the inner wall surface of the outlet-side reactor body member 3 will peel and fall off, and, as a result, a significant deterioration in catalytic action will result.
On the other hand, in order to avoid the occurrence of the disadvantages mentioned above, a moisture generating reactor structured to advance heat dissipation from the reactor body 1 has been developed by providing cooling fins 10 and 11 on the outer wall surface of the inlet-side reactor body member 2 and on the outer wall surface of the outlet-side reactor body member, respectively, as shown in FIG. 9. In FIG. 9, reference numeral 12 designates an electric heater that is used to raise the temperature of the moisture generating reactor 1 to nearly 300° C. when the moisture generating reactor 1 is started.
However, a problem resides in the fact that the disposition of the cooling fins 10 and 11 leads to a great increase in outside dimensions of the moisture generating reactor 1, and, if the amount of moisture generation is made, for example, 1.3 times as great as the conventional amount of moisture generation, the volume of the reactor 1 must be tripled, and hence it is impossible to meet the requirement of reducing the moisture generating reactor 1 in size. A possible method for increasing the amount of moisture generation, without using the cooling fins 10 and 11, is to increase the outside dimensions of the reactor body 1. However, if the area in which the platinum coating film 9 is formed exceeds a predetermined area, unevenness will occur in the temperature distribution on the inner surface of the outlet-side reactor body member 3 when moisture is generated, and, as a result, the platinum coating film 9 may readily peel off. Therefore, another problem resides in the fact that, if the inner diameter of the reactor body 1 is made, for example, twice or more as large as the conventional one, the frequency of occurrence of peeling off of the platinum coating film 9 will rise steeply, as is well known, and the requirement of increasing the amount of moisture generation cannot be satisfactorily met.
Therefore, when employing the above-described type of conventional equipment for supplying moisture gas W, a plurality of moisture generating reactors may be connected in parallel with each other. Then, the flow rate of mixed gas G supplied to each moisture generating reactor is controlled by use of a highly accurate apparatus (i.e., a mixed-gas-flow-dividing-and-supplying apparatus) that divides the flow of the mixed gas G and that supplies the gas to each moisture generating reactor in order to meet the requirement of increasing the amount of moisture generation (i.e., the amount of moisture that needs to be supplied).
However, still another problem resides in the fact that the disposition of the highly accurate apparatus for dividing the flow of the mixed gas G, and supplying the gas, brings about not only a steep rise in the amount of equipment employed, but also brings about the need for a large space for the installation of the equipment, and furthermore, it increases costs for the maintenance, or the like, of the mixed-gas-flow-dividing-and-supplying apparatus.    Patent Literature 1: International Publication No. WO97/28085    Patent Literature 2: Japanese Patent No. 3639469